Cationic electrodeposition coating composition

ABSTRACT

Object: To provide a coated article having excellent anti-corrosion properties on untreated steel sheets. 
     Means for Achieving the Object: The present invention provides a cationic electrodeposition coating composition including amino group-containing modified epoxy resin (A), blocked polyisocyanate curing agent (B), phenol resin (C), metal compound (D), and nitrogen oxide ion (E), wherein the metal compound (D) is contained in an amount of 10 to 10,000 ppm calculated as metal and the nitrogen oxide ion (E) is contained in an amount of 50 to 10,000 ppm, relative to the mass of the cationic electrodeposition coating composition.

TECHNICAL FIELD

The present invention relates to a cationic electrodeposition coatingcomposition that exhibits, without containing toxic substances such aslead compounds, chromium compounds, etc., excellent anti-corrosionproperties, particularly on untreated steel sheets.

BACKGROUND ART

Because of their excellent throwing power and low environmental impact,cationic electrodeposition coating compositions are widely used forvarious applications such as undercoating compositions for automobilesetc. Cationic electrodeposition coating compositions that contain leadcompounds and/or chromium compounds, e.g., lead chromate, basic leadsilicate, and strontium chromate, have been suggested.

However, because of problems with environmental pollution, the use oftoxic compounds such as lead compounds and chromium compounds isrestricted; and a cationic electrodeposition coating composition thatuses a non-toxic or low-toxic rust-preventive pigment, and providesexcellent anti-corrosion properties without containing harmful compoundshas been developed and is now in use.

For example, Patent Literature 1 discloses a cationic electrodepositioncoating composition that comprises (A) a cationic amine modified epoxyresin, (B) a blocked polyisocyanate, and (C) a phosphorous acid divalentor trivalent metal salt, the purpose thereof being to improveanti-corrosion properties without containing lead. Patent Literature 2discloses a zirconium compound-containing cationic electrodepositioncoating composition that exhibits excellent anti-corrosion propertieswithout containing lead.

Patent Literatures 1 and 2 disclose that a film formed on asurface-treated steel sheet has excellent anti-corrosion properties evenwithout containing toxic substances such as lead compounds and chromiumcompounds. However, an electrodeposition coating film formed on asurface-untreated steel sheet has insufficient anti-corrosionproperties.

Patent Literature 3 discloses a cationic electrodeposition coatingcomposition comprising a cationic amine modified epoxy resin, a blockedpolyisocyanate, and a zirconium salt, the purpose thereof being toimprove rust preventive properties to the greatest extent possible.Patent Literature 3 teaches that the composition can provide, evenwithout containing harmful compounds such as lead compounds, chromiumcompounds, etc., an electrodeposition coating film having excellentanti-corrosion properties on a surface-untreated steel sheet.

However, under severely corrosive conditions, the aforementionedelectrodeposition coating film formed on the surface-untreated steelsheet exhibits insufficient anti-corrosion properties; in particular, anelectrodeposition coating film having a thickness of 15 μm or less (whendried) that is formed on an untreated steel sheet exhibits insufficientanti-corrosion properties. Accordingly, further improvement has beendesired.

[Citation List]

[Patent Literature]

[PTL 1] Japanese Unexamined Patent Publication No. H9-241546

[PTL 2] Japanese Unexamined Patent Publication No. 2000-290542

[PTL 3] Japanese Unexamined Patent Publication No. 2009-46628

SUMMARY OF INVENTION Technical Problem

The object of the present invention is to make, without using leadcompounds, chromium compounds, and like toxic substances, a cationicelectrodeposition coating composition that exhibits excellentanti-corrosion properties on an untreated steel sheet, in particular acationic electrodeposition coating composition that exhibits excellentanti-corrosion properties on an untreated steel sheet even when theformed coating film is an electrodeposition coating film having athickness of 15 μm or less (when dried).

Solution to Problem

The present inventors have conducted extensive research to achieve theabove object, and found that the object can be attained by a cationicelectrodeposition coating composition comprising amino group-containingmodified epoxy resin (A), blocked polyisocyanate curing agent (B),phenol resin (C), metal compound (D), and nitrogen oxide ion (E). Thepresent invention was thus accomplished.

Specifically, the present invention provides the following items.

Item 1

A cationic electrodeposition coating composition comprising aminogroup-containing modified epoxy resin (A), blocked polyisocyanate curingagent (B), phenol resin (C), metal compound (D), and nitrogen oxide ion(E);

the cationic electrodeposition coating composition comprising the metalcompound (D) in an amount of 10 to 10,000 ppm calculated as metal (on ametal mass basis), and the nitrogen oxide ion (E) in an amount of 50 to10,000 ppm, relative to the mass of the cationic electrodepositioncoating composition, the amino group-containing modified epoxy resin (A)being a resin obtainable by reacting modified epoxy resin (A1) having anepoxy equivalent of 500 to 2,500 and amine compound (A2),

the modified epoxy resin (A1) being obtainable by reacting diepoxycompound (a1), epoxy resin (a2) having an epoxy equivalent of 170 to500, and bisphenol compound (a3), the diepoxy compound (a1) beingcompound (1) represented by Formula (1) below,

wherein R¹ is the same or different, and each represents a hydrogen atomor a O₁₋₆ alkyl group; R² is the same or different, and each representsa hydroxy atom or C₁₋₂ alkyl group, and m and n, which represent thenumber of repeating units of the portion having an alkylene oxidestructure, are integers where m+n=1 to 20,and/or compound (2) represented by Formula (2) below,

wherein R³ represents a hydrogen atom or C₁₋₆ alkyl group, X is aninteger of 1 to 9, and Y is an integer of 1 to 50; when Y is 2 or more,each R³ in the repeating unit is the same or different, and the metalcompound (D) being a compound of at least one metal (d) selected fromthe group consisting of zirconium, titanium, cobalt, vanadium, tungsten,molybdenum, copper, indium, zinc, aluminum, bismuth, yttrium,lanthanoids, alkali metals, and alkaline earth metals.

Item 2

The cationic electrodeposition coating composition according to Item 1,wherein the amino group-containing modified epoxy resin (A) is containedin an amount of 30 to 75 parts by mass, the blocked polyisocyanatecuring agent (B) is contained in an amount of 10 to 40 parts by mass,and the phenol resin (C) is contained in an amount of 3 to 35 parts bymass, based on the total solids mass (100 parts by mass) of the aminogroup-containing modified epoxy resin (A), blocked polyisocyanate curingagent (B), and phenol resin (C).

Item 3

The cationic electrodeposition coating composition according to Item 1or 2, wherein the modified epoxy resin (A1) is obtainable by reacting 1to 35 mass % of the diepoxy compound (a1), 10 to 80 mass % of the epoxyresin (a2), and 10 to 60 mass % of the bisphenol compound (a3), based onthe total solids mass of the diepoxy compound (a1), epoxy resin (a2),and bisphenol compound (a3).

Item 4

The cationic electrodeposition coating composition according to any oneof Items 1 to 3, wherein R¹ in the Formula (1) or R³ in the Formula (2)is a methyl group or hydrogen atom.

Item 5

The cationic electrodeposition coating composition according to any oneof Items 1 to 4, wherein the metal compound (D) consists of a zirconiumcompound, or comprises at least one compound selected from the groupconsisting of zirconium compounds and titanium compounds, and a compoundof at least one metal selected from the group consisting of cobalt,vanadium, tungsten, molybdenum, copper, indium, zinc, aluminum, bismuth,yttrium, lanthanoids, alkali metals, and alkaline earth metals.

Item 6

The cationic electrodeposition coating composition according to any oneof Items 1 to 5, wherein the solids content of the cationicelectrodeposition coating composition is 5 to 40 mass %.

Item 7

A coated article obtainable by immersing a metal substrate in anelectrodeposition coating composition bath containing the cationicelectrodeposition coating composition according to any one of Items 1 to6, and performing electrodeposition coating.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the cationic electrodeposition coating composition of thepresent invention, a coated article that has excellent anti-corrosionproperties on an untreated steel sheet, in particular, excellentanti-corrosion properties on an untreated steel sheet even when theformed coating film is a thin film with a thickness of 15 μm or less(when dried), can be obtained without containing toxic metals such aslead compounds, chromium compounds, etc. For this reason, the cationicelectrodeposition coating composition of the present invention is usefulfor the electrodeposition coating of automobile bodies and parts,electrical appliances, etc.

There is no particular limitation on the method for producing a coatingfilm using the cationic electrodeposition coating composition of thepresent invention. If a two-step method including immersion andelectrodeposition is applied, a film (lower layer) mainly comprisinginorganic components can be first formed by allowing metal compound (D)to be selectively deposited on the substrate, and then a film (upperlayer) mainly comprising organic components can be formed by allowingresin components etc. that comprise amino group-containing modifiedepoxy resin (A) and blocked polyisocyanate curing agent (B) to bedeposited on the film (lower layer). Thus, the lower layer that containsmetal oxide having passivation can be formed on the surface of a metalsubstrate such as an untreated steel sheet, which contributes to theinhibition of corrosion under the film. Further, the addition of phenolresin (C) can improve adhesion with the substrate, which ensures afurther improvement in anti-corrosion properties.

Still further, diepoxy compound (a1) used in amino group-containingmodified epoxy resin (A) can help to provide a coated article that hasexcellent bath (liquid) stability and anti-corrosion properties overtime even though the cationic electrodeposition coating compositionincludes metal compound (D) and nitrogen oxide ion (E).

DESCRIPTION OF EMBODIMENTS

The present invention relates to a cationic electrodeposition coatingcomposition that comprises amino group-containing modified epoxy resin(A), blocked polyisocyanate curing agent (B), phenol resin (C), metalcompound (D), and nitrogen oxide ion (E), wherein metal compound (D) iscontained in an amount of 10 to 10,000 ppm calculated as metal, andnitrogen oxide ion (E) is contained in an amount of 50 to 10,000 ppm,relative to the mass of the cationic electrodeposition coatingcomposition.

The present invention is detailed below.

Amino Group-Containing Modified Epoxy Resin (A)

Amino group-containing modified epoxy resin (A) for use in the presentinvention is a resin obtainable by reacting modified epoxy resin (A1)having an epoxy equivalent of 500 to 2,500 with amine compound (A2).

The aforementioned modified epoxy resin (A1) is a resin obtainable byreacting diepoxy compound (a1), i.e., compound (1) represented byFormula (1) and/or compound (2) represented by Formula (2); epoxy resin(a2) having an epoxy equivalent of 170 to 500; and bisphenol compound(a3).

Modified Epoxy Resin (A1) Having an Epoxy Equivalent of 500 to 2,500:

The aforementioned modified epoxy resin (A1) is a modified epoxy resinhaving an epoxy equivalent of 500 to 2,500 that is obtainable byreacting specific diepoxy compound (a1), epoxy resin (a2) having anepoxy equivalent of 170 to 500, and bisphenol compound (a3).

Diepoxy Compound (a1)

As diepoxy compound (a1), compound (1) represented by Formula (1) can beused,

wherein R¹ is the same or different, and each represents a hydrogen atomor a C₁₋₆ alkyl group; R² is the same or different, and each representsa hydrogen atom or a C₁₋₂ alkyl group; m and n, which represent thenumber of repeating units of the portion having an alkylene oxidestructure, are integers where m+n=1 to 20.

In Formula (1), when at least either m or n represents 2 or more, eachR¹ in the repeating unit “m”, and each R¹ in the repeating unit “n” maybe the same or different.

Compound (1) can be produced by adding alkylene oxide represented byFormula (3) below,

wherein R⁴ represents a hydrogen atom or a C₁₋₆ alkyl group, tobisphenol A, bisphenol F, etc., to obtain a hydroxy-terminated polyethercompound, and then allowing the polyether compound to react withepihalohydrin to obtain a diepoxy compound.

Examples of alkylene oxide represented by Formula (3) include ethyleneoxide, propylene oxide, butylene oxide, hexylene oxide, octylene oxideand like C₂₋₈ alkylene oxides.

Of these, ethylene oxide (compound in which R⁴ in Formula (3) is ahydrogen atom) and propylene oxide (compound in which R⁴ in Formula (3)is a methyl group) are preferable.

Compound (2):

As diepoxy compound (a1), compound (2) represented by Formula (2) can beused,

wherein R³ represents a hydrogen atom or a C₁₋₆ alkyl group; Xrepresents 1 to 9; and Y is an integer of 1 to 50. When Y is 2 or more,R³ in the repeating unit may be the same or different.

Examples of the method for producing compound (2) include method (1) inwhich alkylene oxide represented by Formula (2) is subjected toring-opening polymerization using alkylene glycol as a startingmaterial, thereby obtaining hydroxyl-terminated polyalkylene oxide, andthe polyalkylene oxide is allowed to react with epihalohydrin to form adiepoxy compound.

Another example of the method for producing compound (2) is method (2)in which alkylene glycol represented by Formula (4) or polyether diolobtained by condensing two or more alkylene glycol molecules bydehydration, is allowed to react with epihalohydrin to form a diepoxycompound,

wherein R⁵ represents a hydrogen atom or a C₁₋₆ alkyl group, and X is aninteger of 1 to 9.

Examples of alkylene glycol represented by Formula (4) used hereininclude ethylene glycol, propylene glycol, trimethylene glycol,1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol,1,8-octanediol, 1,9-nonandiol and like C₂₋₁₀ alkylene glycols.

Examples of diepoxy compound (a1) represented by Formula (1) or Formula(2) include Denacol EX-850, Denacol EX-821, Denacol EX-830, DenacolEX-841, Denacol EX-861, Denacol EX Denacol EX-920, Denacol EX-931(produced by Nagase ChemteX Corporation); Glyci-ale PP-300P andGlyci-ale BPP-350 (produced by Sanyo Chemical Industries, Ltd.); etc. Asdiepoxy compound (a1), compounds (1) and (2) may be used in combination.

Epoxy Resin (a2) Having an Epoxy Equivalent of 170 to 500

In the present invention, epoxy resin (a2) having an epoxy equivalent of170 to 500 (hereinafter sometimes simply referred to as epoxy resin(a2)) for use in the production of modified epoxy resin (A1) having anepoxy equivalent of 500 to 2,500 includes compounds having two or moreepoxy groups per molecule, and an epoxy equivalent of 170 to 500,preferably 170 to 400, excluding diepoxy compound (a1), i.e., compound(1) represented by Formula (1) and compound (2) represented by Formula(2). Suitable epoxy resin (a2) has a number average molecular weight of340 to 1,500, and preferably 340 to 1,000. In particular, epoxy resin(a2), which can be obtained by reacting a polyphenol compound withepihalohydrin, is preferable.

The “number average molecular weight” herein is a value determinedaccording to the method of JIS K 0124-83, from a chromatogram measuredby gel permeation chromatograph, based on the molecular weight ofstandard polystyrene. For a gel permeation chromatograph, “HLC8120GPC”(produced by Tosoh Corporation) was used. The measurement was conductedusing four columns, “TSK GEL G-4000HXL”, “TSK GEL G-3000HXL”, “TSK GELG-2500HXL”, and “TSK GEL G-2000HXL” (trade names; produced by TosohCorporation), under the following conditions: mobile phase:tetrahydrofuran, measuring temperature: 40° C., flow rate: 1 ml/min, anddetector: R¹.

Examples of polyphenol compounds used for forming such epoxy resinsinclude bis(4-hydroxyphenyl)-2,2-propane (bisphenol A),bis(4-hydroxyphenyl)methane (bisphenol F),bis(4-hydroxycyclohexyl)methane (hydrogenated bisphenol F),2,2-bis(4-hydroxycyclohexyl)propane (hydrogenated bisphenol A),4,4′-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane,hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-2 or3-tert-butyl-phenyl)-2,2-propane, bis(2-hydroxynaphthyl)methane,tetra(4-hydroxyphenyl)-1,1,2,2-ethane, 4,4′-dihydroxydiphenylsulfone,phenol novolac, cresol novolac, etc.

Of the epoxy resins obtainable by reacting a polyphenol compound withepichlorohydrin, those of the following Formula (5) derived frombisphenol A are preferable,

wherein n is 0 to 2.

Examples of commercial products of such epoxy resins include thoseavailable from Japan Epoxy Resins Co., Ltd. under the trade names ofjER828EL and jER1001.

Bisphenol Compound (a3):

Examples of bisphenol compound (a3) include those represented by Formula(6) below,

wherein R⁶ and R⁷ each represents a hydrogen atom or a C₁₋₆ alkyl group;and R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, and R¹⁵ are the same or different,and each represents a hydrogen atom or a C₁₋₆ alkyl group.

Specific examples thereof include bis(4-hydroxyphenyl)-2,2-propane(bisphenol A), bis(4-hydroxyphenyl)methane (bisphenol F), etc.

In general, modified epoxy resin (A1) having an epoxy equivalent of 500to 2,500 can be produced by mixing diepoxy compound (a1), epoxy resin(a2) having an epoxy equivalent of 170 to 500, and bisphenol compound(a3), and reacting these three compounds in the presence of a suitablyselected reaction catalyst such as dimethylbenzylamine, tributylamine,or like tertiary amines; tetraethylammonium bromide, tetrabutylammoniumbromide or like quaternary ammonium salts, at a reaction temperature ofabout 80° C. to 200° C., and preferably about 90° C. to 180° C., for 1to 6 hours, and preferably 1 to 5 hours.

Examples of methods for producing modified epoxy resin (A1) are asfollows (Methods 1 to 3).

1. A method in which diepoxy compound (a1), epoxy resin (a2) having anepoxy equivalent of 170 to 500, and bisphenol compound (a3) are allmixed and reacted with each other to produce modified epoxy resin (A1)having an epoxy equivalent of 500 to 2,500.2. A method in which diepoxy compound (a1) and bisphenol compound (a3)are reacted to yield a reaction mixture, after which epoxy resin (a2)having an epoxy equivalent of 170 to 500 is added and reacted with thereaction mixture to produce modified epoxy resin (A1) having an epoxyequivalent of 500 to 2,500.3. A method in which epoxy resin (a2) having an epoxy equivalent of 170to 500 is reacted with bisphenol compound (a3) to yield a reactionmixture, after which diepoxy compound (a1) is added and reacted with thereaction mixture to produce modified epoxy resin (A1) having an epoxyequivalent of 500 to 2,500. The reaction state can be traced by epoxyvalue.

In the production of modified epoxy resin (A1), the proportion ofdiepoxy compound (a1) is preferably 1 to 35 mass %, and more preferably2 to 30 mass %, based on the total solids mass of the components forforming modified epoxy resin (A1), i.e., diepoxy compound (a1), epoxyresin (a2) having an epoxy equivalent of 170 to 500, and bisphenolcompound (a3). The proportion in the above range is preferable to attainexcellent water dispersibility of amino group-containing modified epoxyresin (A) and excellent bath (liquid) stability even when the cationicelectrodeposition coating composition includes metal compound (D) andnitrogen oxide ion (E), and to improve anti-corrosion properties on anuntreated steel sheet, particularly anti-corrosion properties on anuntreated steel sheet even when the formed coating film is a thin filmhaving a thickness of 15 μm or less (when dried).

Further, to provide a coating film having excellent anti-corrosionproperties on an untreated steel sheet, particularly when the formedcoating film has a thickness of 15 μm or less (when dried), it ispreferable that the proportion of epoxy resin (a2) having an epoxyequivalent of 170 to 500 be 10 to 80 mass %, particularly 15 to 75 mass%, and the proportion of bisphenol compound (a3) be 10 to 60 mass %,particularly 15 to 50 mass %.

In the above production, an organic solvent may be optionally used.Examples thereof include toluene, xylene, cyclohexane, n-hexane and likehydrocarbon-based solvents; methyl acetate, ethyl acetate, butyl acetateand like ester-based solvents; acetone, methyl ethyl ketone, methylisobutyl ketone, methyl amyl ketone and like ketone-based solvents;dimethyl formamide, dimethyl acetamide and like amide-based solvents;methanol, ethanol, n-propanol, isopropanol and like alcohol-basedsolvents; phenylcarbinol, methylphenylcarbinol and like aromatic alkylalcohol-based solvents; ethylene glycol monobutyl ether, diethyleneglycol monoethyl ether and like ether alcohol-based solvents; andmixtures thereof, etc.

Amine Compound (A2)

Amino group-containing modified epoxy resin (A) can be obtained bysubjecting modified epoxy resin (A1) to an addition reaction with aminecompound (A2). Examples of amine compound (A2) include mono- ordialkylamines such as monomethylamine, dimethylamine, monoethylamine,diethylamine, monoisopropylamine, diisopropylamine, monobutylamine,dibutylamine, etc.; alkanolamines such as monoethanolamine,diethanolamine, mono(2-hydroxypropyl)amine, di(2-hydroxypropyl)amine,monomethylaminoethanol, monoethylaminoethanol, monoethylaminobutanol,etc.; alkylene polyamines and ketiminized compounds of these polyaminessuch as ethylenediamine, propylenediamine, butylenediamine,hexamethylenediamine, tetraethylenepentamine, pentaethylenehexamine,diethylaminopropylamine, diethylenetriamine, triethylenetetramine, etc.;alkyleneimines such as ethyleneimine, propyleneimine, etc.; cyclicamines such as piperazine, morpholine, pyrazine, etc. Among theabove-mentioned amines, it is also possible to use as amine compound(A2), ketiminized amines obtained by ketiminizing primary amines (forexample, ketimine of diethylenetriamine with methyl isobutyl ketone,etc.). Amines obtained by ketiminizing primary amines can be used incombination with the amines listed above.

The proportion of each component used in the aforementioned additionreaction of modified epoxy resin (A1) and amine compound (A2) is notstrictly limited, and can be suitably determined according to the useetc., of the cationic electrodeposition coating composition. Theproportion of modified epoxy resin (A1) is 70 to 98 mass %, preferably75 to 96 mass %, and the proportion of amine compound (A2) is 2 to 30mass %, preferably 4 to 25 mass %, based on the total solids mass ofmodified epoxy resin (A1) and amine compound (A2) used in the productionof amino group-containing modified epoxy resin (A). The additionreaction is usually carried out in a suitable solvent at 80° C. to 170°C., and preferably 90° C. to 150° C. for 1 to 6 hours, and preferably 1to 5 hours. Examples of the solvent used in the above reaction includehydrocarbon-based solvents such as toluene, xylene, cyclohexane,n-hexane, etc.; ester-based solvents such as methyl acetate, ethylacetate, butyl acetate, etc.; ketone-based solvents such as acetone,methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, etc.;amide-based solvents such as dimethylformamide, dimethylacetamide, etc.;alcohol-based solvents such as methanol, ethanol, n-propanol,iso-propanol, etc.; aromatic alkyl alcohol-based solvents such as phenylcarbinol, methyl phenyl carbinol, etc.; ether alcohol-based solventssuch as ethylene glycol monobutyl ether, diethylene glycol monoethylether, etc.; and mixtures thereof, etc.

Blocked Polyisocyanate Curing Agent (B)

The combination use of amino group-containing modified epoxy resin (A)with blocked polyisocyanate curing agent (B) can provide a heat curablecationic electrodeposition coating composition.

Blocked polyisocyanate curing agent (B) is an addition-reaction productin almost stoichiometric amount of a polyisocyanate compound and anisocyanate blocking agent. Polyisocyanate compounds usable in blockedpolyisocyanate curing agent (B) may be known compounds. Examples thereofinclude aromatic, aliphatic or alicyclic polyisocyanate compounds suchas tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate,diphenylmethane-2,2′-diisocyanate, diphenylmethane-2,4′-diisocyanate,diphenylmethane-4,4′-diisocyanate, crude MDI (polymethylene polyphenylisocyanate), bis(isocyanatemethyl)cyclohexane, tetramethylenediisocyanate, hexamethylene diisocyanate, methylene diisocyanate,isophorone diisocyanate, etc.; cyclopolymers or biurets of thesepolyisocyanate compounds; and combinations thereof.

Specifically, tolylene diisocyanate, xylylene diisocyanate, phenylenediisocyanate, diphenylmethane-2,4′-diisocyanate,diphenylmethane-4,4′-diisocyanate, crude MDI, and like aromaticpolyisocyanate compounds are particularly preferable in view ofanti-corrosion properties.

The isocyanate blocking agent is added to isocyanate groups of apolyisocyanate compound to block the isocyanate groups. The blockedpolyisocyanate compound obtained by such an addition is stable at roomtemperature; however, it is desirable that the blocking agent bedissociated to regenerate free isocyanate groups, when heated to thebaking temperature of a coating film (usually about 100° C. to about200° C.).

Examples of blocking agents usable in blocked polyisocyanate curingagent (B) include methylethylketoxime, cyclohexanone oxime and likeoxime-based compounds; phenol, para-t-butylphenol, cresol and likephenol-based compounds; n-butanol, 2-ethylhexanol and like aliphaticalcohol-based compounds; phenylcarbinol, methylphenylcarbinol and likearomatic alkyl alcohol-based compounds; ethylene glycol monobutyl ether,diethylene glycol monoethyl ether and like ether alcohol-basedcompounds; ε-caprolactam, γ-butyrolactam and like lactam-basedcompounds; etc.

Phenol Resin (C)

Phenol resin (C) is a resin obtained by subjecting a phenol-basedcompound such as phenol, cresol, bisphenol A, etc. and an aldehyde-basedcompound such as formaldehyde etc. to a condensation reaction in thepresence of an acid catalyst, basic catalyst, or the like. Of these,resins condensed by an acid catalyst are referred to as novolac phenolresins; and resins condensed by a basic catalyst are referred to asresol phenol resins.

In the present invention, both novolac phenol resins and resol phenolresins can be used. Usable resins include resins obtained by introducinga methylol group, and phenol resins in which the introduced methylolgroup is partially or wholly alkyl-etherified with an alcohol having 6or less carbon atoms.

To improve adhesion of the resulting coating film, and obtain a coatingfilm having excellent anti-corrosion properties on an untreated steelsheet even when the formed film is a thin film with a thickness of 15 μmor less, phenol resin (C) used in the present invention preferably has ahydroxy value of 90 to 623 mg KOH/g.

Commercially available phenol resin (C) includes SUMILITERESIN PR-HF-3,SUMILITERESIN PR-HF-6, SUMILITERESIN PR-53194, SUMILITERESIN PR-53195,SUMILITERESIN PR-54869, SUMILITERESIN PR-16382, SUMILITERESIN PR-51939,SUMILITERESIN PR-53153, SUMILITERESIN PR-53364, SUMILITERESIN PR-53365,and SUMILITERESIN PR-50702 (all produced by Sumitomo Bakelite Co.,Ltd.); PHENOLITE TD-2131, PHENOLITE TD-2106, PHENOLITE TD-2093,PHENOLITE TD-2091, PHENOLITE TD-2090, PHENOLITE VH-4150, PHENOLITEVH-4170, PHENOLITE VH-4240, PHENOLITE KH-1160, PHENOLITE KH-1163,PHENOLITE KH-1165, PHENOLITE TD-2093-60M, PHENOLITE TD-2090-60M,PHENOLITE LF-4711, PHENOLITE LF-6161, PHENOLITE LF-4871, PHENOLITELA-7052, PHENOLITE LA-7054, PHENOLITE LA-7751, PHENOLITE LA-1356, andPHENOLITE LA-3018-50P (produced by DIC Corporation); Shonol BRG-555,Shonol BRG-556, Shonol BRG-558, Shonol CKM-923, Shonol CKM-983, ShonolBKM-2620, Shonol BRL-2854, Shonol BRG-5590M, Shonol CKS-3898, ShonolCKS-3877A, and Shonol CKM-937 (produced by “Showa Highpolymer Co.,Ltd”); Maruka Lyncur M-S-1, Maruka Lyncur M-S-2, Maruka Lyncur M-S-3,and Maruka Lyncur CST (produced by “Maruzen Petrochemical Co., Ltd.”);Nikanol NP-100, Nikanol P-100, Nikanol HP-150, Nikanol PR-1440 (producedby FUDOW Co., Ltd.), etc.

In the cationic electrodeposition coating composition of the presentinvention, it is preferable that amino group-containing modified epoxyresin (A) be contained in an amount of 30 to 75 parts by mass,preferably 30 to 65 parts by mass, blocked polyisocyanate curing agent(B) be contained in an amount of 10 to 40 parts by mass, preferably 10to 35 parts by mass, and phenol resin (C) be contained in an amount of 3to 35 parts by mass, preferably 4 to 32 parts by mass, per 100 parts bymass of the total solids content of the components (A), (B), and (C).Each component in the above range is preferable to improve theanti-corrosion properties of the coating film on the untreated steelsheet.

Metal Compound (D)

The cationic electrodeposition coating composition of the presentinvention comprises metal compound (D). Metal compound (D) is a compoundof at least one metal (d) selected from the group consisting ofzirconium, titanium, cobalt, vanadium, tungsten, molybdenum, copper,indium, zinc, aluminum, bismuth, yttrium, lanthanide metals, alkalimetals, and alkali earth metals. Of these, water-soluble metal compoundsare preferable.

Examples of zirconium compounds include zirconium chloride, zirconylchloride, zirconium sulfate, zirconyl sulfate, zirconium nitrate,zirconyl nitrate, zirconium hydrofluoric acid, zirconium hydrofluoricacid salts, zirconium oxide, zirconyl bromide, zirconyl acetate,zirconyl carbonate, zirconium fluoride, etc.

Examples of titanium compounds include titanium chloride, titaniumsulfate, titanyl sulfate, titanium nitrate, titanyl nitrate, titaniumhydrofluoric acid, titanium hydrofluoric acid salts, titanium oxide,titanium fluoride, etc.

Examples of cobalt compounds include cobalt chloride, cobalt bromide,cobalt iodide, cobalt nitrate, cobalt sulfate, cobalt acetate, ammoniumcobalt sulfate, etc. Of these, cobalt nitrate is particularly preferred.

Examples of vanadium compounds include lithium orthovanadate, sodiumorthovanadate, lithium metavanadate, potassium metavanadate, sodiummetavanadate, ammonium metavanadate, sodium pyrovanadate, vanadylchloride, vanadyl sulfate, etc.

Examples of tungsten compounds include lithium tungstate, sodiumtungstate, potassium tungstate, ammonium tungstate, sodiummetatungstate, sodium paratungstate, ammonium pentatungstate, ammoniumheptatungstate, sodium phosphotungstate, barium borotungstate, etc.

Examples of molybdenum compounds include lithium molybdate, sodiummolybdate, potassium molybdate, ammonium heptamolybdate, calciummolybdate, magnesium molybdate, strontium molybdate, barium molybdate,phosphomolybdate, sodium phosphomolybdate, zinc phosphomolybdate, etc.

Examples of copper compounds include copper sulfate, copper(II) nitratetrihydrate, copper(II) ammonium sulfate hexahydrate, copper (II) oxide,copper phosphate, etc.

Examples of indium compounds include ammonium indium nitrate etc.

Examples of zinc compounds include zinc acetate, zinc lactate, zincoxide, zinc nitrate, etc.

Examples of aluminum compounds include aluminum nitrate etc.

Examples of bismuth compounds include inorganic bismuth-containingcompounds such as bismuth chloride, bismuth oxychloride, bismuthbromide, bismuth silicate, bismuth hydroxide, bismuth trioxide, bismuthnitrate, bismuth nitrite, bismuth oxycarbonate, etc.; and bismuthlactate, triphenylbismuth, bismuth gallate, bismuth benzoate, bismuthcitrate, bismuth methoxyacetate, bismuth acetate, bismuth formate,bismuth 2,2-dimethylolpropionate, etc.

Examples of yttrium compounds include yttrium nitrate, yttrium formate,yttrium acetate, yttrium chloride, yttrium sulfamate, yttrium lactate,yttrium hypophosphite, etc.

Examples of lanthanoid metal compounds include lanthanum compounds suchas lanthanum nitrate, lanthanum fluoride, lanthanum acetate, lanthanumboride, lanthanum phosphate, and lanthanum carbonate; cerium compoundssuch as cerium nitrate, cerium chloride, cerium acetate, cerium formate,cerium lactate, cerium oxalate, cerium ammonium nitrate, ceriumsulfamate, diammonium cerium nitrate, and cerium hypophosphite;praseodymium compounds such as praseodymium nitrate, praseodymiumsulfate, praseodymium formate, praseodymium acetate, praseodymiumsulfate, praseodymium oxalate, and praseodymium hypophosphate; neodymiumcompounds such as neodymium nitrate, neodymium formate, neodymiumacetate, neodymium lactate, neodymium sulfamate, neodymium oxide, andneodymium hypophosphite; samarium compounds such as samarium acetate,samarium formate, and samarium sulfamate; etc.

Examples of compounds of alkali metals (at least one metal selected fromthe group consisting of lithium, sodium, potassium, rubidium, cesium,and francium) include lithium tungstate, sodium tungstate, potassiumtungstate, etc.

Examples of compounds of alkaline earth metals (at least one metalselected from the group consisting of beryllium, magnesium, calcium,strontium, barium, and radium) include calcium molybdate, magnesiummolybdate, strontium molybdate, barium molybdate, etc.

In a preferable embodiment, the following are usable as metal compound(D), which is contained in the cationic electrodeposition coatingcomposition of the present invention:

(1): compounds of at least one metal (d) selected from the groupconsisting of zirconium, titanium, cobalt, vanadium, tungsten,molybdenum, copper, indium, zinc, aluminum, bismuth, yttrium, lanthanidemetals, alkali metals, and alkali earth metals.(2): compounds consisting of a zirconium compound, or a combination of azirconium compound and a compound of at least one metal (d) selectedfrom the group consisting of titanium, cobalt, vanadium, tungsten,molybdenum, copper, indium, zinc, aluminum, bismuth, yttrium, lanthanidemetals, alkali metals, and alkali earth metals.(3): compounds consisting of a combination of at least one compoundselected from zirconium compounds and titanium compounds, and a compoundof at least one metal selected from the group consisting of cobalt,vanadium, tungsten, molybdenum, copper, indium, zinc, aluminum, bismuth,yttrium, lanthanide metals, alkali metals, and alkali earth metals.

To improve the anti-corrosion properties on the untreated steel sheet,the amount of metal compound (D) used in the present invention is 10 to10,000 ppm, and preferably 20 to 8,000 ppm calculated as metal, relativeto the mass of the cationic electrodeposition coating composition.

Adding metal compound (D) so that the mass of metal is within theabove-mentioned range is preferable to improve the anti-corrosionproperties of the film on the untreated steel sheet without severelyimpairing coating composition stability even in the case that the formedcoating film is a thin film with a thickness of 15 μm or less (whendried). Among metal compound (D), if metal nitrate is used, examples ofthe cationic electrodeposition coating composition of the presentinvention include those in which metal compound (D) is added to asolvent as well as those in which metal (d) and nitrogen oxide ion (E)are added to a solvent.

Nitrogen Oxide Ion (E)

The cationic electrodeposition coating composition of the presentinvention comprises nitrogen oxide ion (E). Nitrogen oxide ion (E) is ageneral term for nitrate ion, nitrite ion, etc. Examples of the cationicelectrodeposition coating composition of the present invention includethose in which a nitrogen oxide ion is added to a solvent etc., as wellas those in which a compound that generates or contains a nitrogen oxideion is added, thereby containing a nitrogen oxide ion in the cationicelectrodeposition coating composition. Examples of compounds thatgenerate or contain a nitrogen oxide ion include nitric acid, metalnitrate, metal nitrite, etc.

Examples of nitric acid, metal nitrate, and metal nitrite include nitricacid, nitrous acid, zinc nitrate, aluminum nitrate, ytterbium nitrate,yttrium nitrate, indium nitrate, molybdenum nitrate, potassium nitrate,calcium nitrate, silver nitrate, cobalt nitrate, zirconium nitrate,zirconyl nitrate, strontium nitrate, cesium nitrate, cerium nitrate,titanyl nitrate, titanium nitrate, iron nitrate, copper nitrate,samarium nitrate, neodium nitrate, praseodymium nitrate, rutheniumnitrate, lanthanum nitrate, copper nitrate, bismuth nitrate, magnesiumnitrate, zinc nitrite, potassium nitrite, calcium nitrite, ceriumnitrite, cupric nitrite, copper nitrite, barium nitrite, nickel nitrite,magnesium nitrite, etc.

The cationic electrodeposition coating composition can include nitrogenoxide ion (E) by adding at least one member selected from the nitricacids, metal nitrates, and metal nitrites listed above. The amount ofnitrogen oxide ion (E) in a bath of the cationic electrodepositioncoating composition of the present invention is 50 to 10,000 ppm,preferably 100 to 8,000 ppm, relative to the mass of the cationicelectrodeposition coating composition (bath). Adjusting the amount ofnitrogen oxide ion (E) to the above range is preferable because thedeposition of metal compound (D) on the interface (substrate side)between the substrate and the film can be accelerated without impairingcomposition stability. For this reason, the anti-corrosion properties ofthe film on the untreated metal sheet can be improved even when theformed coating film is a thin film with a thickness of 15 μm or less(when dried).

The cationic electrodeposition coating composition of the presentinvention comprises, if necessary, other additives, such as pigments,catalysts, organic solvents, pigment dispersants, surface controlagents, surfactants, etc., in amounts generally used in the field ofcoating compositions. Examples of the pigments and solvents includecoloring pigments such as titanium white, carbon black, etc.; extenderpigments such as clay, talc, baryta, etc.; rust-preventive pigments suchas aluminum dihydrogen tripolyphosphate, aluminum phosphomolybdate,etc.; bismuth compounds such as bismuth oxide, bismuth hydroxide,bismuth lactate, etc.; organic tin compounds such as dibutyltin oxide,dioctyltin oxide, etc.; dialkyl tin aliphatic or aromatic carboxylates,such as dibutyltin dilaurete, dioctyltin dilaurete, dibutyltindiacetate, dioctyltin dibenzoate, dibutyl tin dibenzoate, etc.

The cationic electrodeposition coating composition of the presentinvention can be produced by the following methods (1) to (3).

Method (1): Amino group-containing modified epoxy resin (A), blockedpolyisocyanate curing agent (B), phenol resin (C), and, if necessary,other additives are added and fully mixed to form a dissolution varnish.A neutralizer selected from the group consisting of formic acid, aceticacid, lactic acid, propionic acid, citric acid, malic acid, sulfamicacid, and mixtures of two or more of these acids is added to thedissolution varnish, and dispersed in an aqueous medium, therebyobtaining an emulsion. Metal compound (D) and nitrogen oxide ion (E) arethen added to the emulsion, followed by further addition of pigmentdispersion paste.Method (2): Metal compound (D) and nitrogen oxide ion (E) are mixed. Apigment ingredient, catalyst, other additives, water, etc. are added anddispersed in the mixture, thereby forming a pigment dispersion paste.The pigment dispersion paste is added to an emulsion containing aminogroup-containing modified epoxy resin (A), blocked polyisocyanate curingagent (B), and phenol resin (C).Method (3): Metal compound (D) and nitrogen oxide ion (E) are added tothe bath of the previously prepared cationic electrodeposition coatingcomposition (containing amino group-containing modified epoxy resin (A),blocked polyisocyanate curing agent (B), and phenol resin (C)), anddiluted with water.

The cationic electrodeposition coating composition can be formed by theaforementioned methods (1) to (3), and like equivalent methods.

The cationic electrodeposition coating composition can be produced byadjusting the emulsion and pigment dispersion paste with deionized wateretc., so that the solids content of Bath paint is 5 to 40 mass %,preferably 8 to 25 mass %, and the pH is 1.0 to 9.0, preferably 3.0 to6.5.

There is no particular limitation on the method for producing a coatingfilm using the cationic electrodeposition coating composition of thepresent invention, and any known methods can be used. For example, acoating film can be formed by applying a current to a substrateimmediately after immersing the substrate in the bath of the cationicelectrodeposition coating composition, (referred to as “a one-stepmethod”), or by immersing a substrate in the bath of the cationicelectrodeposition coating composition for a certain period, orperforming electrocrystallization (performing electrodeposition coatingat low voltage), followed by electrodeposition coating (referred to as atwo-step method).

Of the aforementioned two methods, since the method comprising immersingthe substrate in the bath containing the cationic electrodepositioncoating composition of the present invention (Step 1), and thenperforming electrodeposition coating (Step 2) can provide a densepassivation film, such a method is preferable in view of improvinganti-corrosion properties.

In the above described “two-step method”, a film can be formed byimmersing the metal substrate in the bath containing the cationicelectrodeposition coating composition at a temperature of 15° C. to 55°C., preferably 20° C. to 50° C. By immersing the substrate for 10 to 600seconds, preferably 30 to 480 seconds, and more preferably 40 to 300seconds (Step 1), a dense passivation film can be formed on thesubstrate.

Subsequently, by applying an electric current at a voltage of 50 to 400V, preferably 75 to 370 V, for 60 to 600 seconds, preferably 80 to 400seconds (Step 2) using the metal substrate as a cathode, a film can bedeposited on the substrate.

It is preferable to set the temperature of the bath containing thecationic electrodeposition coating composition to 10° C. to 55° C., andparticularly 20° C. to 50° C. since a deposition film having few defectscan be uniformly formed. It is also possible to immerse the metalsubstrate in the electrodeposition coating composition bath, take theimmersed metal substrate out of the bath, and then reimmerse the metalsubstrate in the bath to perform electrodeposition coating.

The two-step coating film production method can sequentially form on thefirst layer film (lower layer), the second layer film (upper layer) thatmainly comprises a resin component, pigment, etc., which are completelydifferent compositions from those of the first layer film, therebyproviding a multiple layer film structure having excellentanti-corrosion properties and finish.

The mechanism for depositing the film using the cationicelectrodeposition coating composition is as follows.

When immersion is conducted in Step 1, the pH in the vicinity of thesubstrate is raised by the etching effect of the nitric acid rootcontained in the cationic electrodeposition coating composition, andmetal ions (for example, zirconium hexafluoride ion etc.) affected bythe hydrolysis reaction cause a poorly-soluble film (lower layer)(mainly, for example, zirconium oxide) to be deposited on the substrate.

The thus obtained coating film is baked and heated at a surfacetemperature of the substrate of 100° C. to 200° C., preferably 120° C.to 180° C. for 5 to 90 minutes, preferably 10 to 50 minutes.

EXAMPLES

The present invention is explained in detail below with reference toproduction examples, examples, and comparative examples; however, thepresent invention is not limited thereto. In the examples, “parts” “and“%” are by mass.

Production of Amino Group-Containing Modified Epoxy Resin (A) ProductionExample 1 Production Example of Base Resin No. 1

A 2-liter flask equipped with a thermometer, a reflux condenser, and astirrer was charged with 296 parts of Glyci-ale PP-300P (Note 1), 1,330parts of jER828EL (Note 4), 684 parts of bisphenol A, and 1.0 parts oftetrabutylammonium bromide. The mixture was allowed to react at 160° C.until the epoxy equivalent became 1,150.

Next, 611 parts of methyl isobutyl ketone, and then 137 parts ofmonomethylaminoethanol were added to the reaction mixture, and allowedto react at 120° C. for 4 hours. The solution of base resin No. 1, whichwas an amino group-containing modified epoxy resin with a resin solidscontent of 80%, was thus obtained. Base resin No. 1 had an amine valueof 41 mg KOH/g, and a number average molecular weight of 2,700.

Production Example 2 Production Example of Base Resin No. 2

A 2-liter flask equipped with a thermometer, a reflux condenser, and astirrer was charged with 185 parts of Denacol EX-821 (Note 2), 950 partsof jER828EL (Note 4), 456 parts of bisphenol A, and 0.8 parts oftetrabutylammonium bromide. The mixture was allowed to react at 160° C.until the epoxy equivalent became 795.

Next, 368 parts of methyl isobutyl ketone, and then 110 parts of diethylamine, and 95 parts of a ketimine of diethylenetriamine with methylisobutyl ketone (purity: 84%, methyl isobutyl ketone solution) wereadded to the reaction mixture, and allowed to react at 120° C. for 4hours. The solution of base resin No. 2, which was an aminogroup-containing modified epoxy resin with a resin solids content of80%, was thus obtained. Base resin No. 2 had an amine value of 68 mgKOH/g, and a number average molecular weight of 2,000.

Production Example 3 Production Example of Base Resin No. 3

A 2-liter flask equipped with a thermometer, a reflux condenser, and astirrer was charged with 340 parts of Glyci-ale BPP-350 (Note 3), 950parts of jER828EL (Note 4), 456 parts of bisphenol A, and 0.8 parts oftetrabutylammonium bromide. The mixture was allowed to react at 160° C.until the epoxy equivalent became 873.

Next, 407 parts of methyl isobutyl ketone, and then 113 parts ofmonomethylaminoethanol, and 95 parts of a ketimine of diethylenetriaminewith methyl isobutyl ketone (purity: 84%, methyl isobutyl ketonesolution) were added to the reaction mixture, and allowed to react at120° C. for 4 hours. The solution of base resin No. 3, which was anamino group-containing modified epoxy resin with a resin solids contentof 80%, was thus obtained. Base resin No. 3 had an amine value of 62 mgKOH/g, and a number average molecular weight of 2,200.

Production Example 4 Production Example of Base Resin No. 4

A 2-liter flask equipped with a thermometer, a reflux condenser, and astirrer was charged with 296 parts of Glyci-ale PP-300P (Note 1), 1,330parts of jER828EL (Note 4), 684 parts of bisphenol A, and 1.0 parts oftetrabutylammonium bromide. The mixture was allowed to react at 160° C.until the epoxy equivalent became 1,150.

Next, 611 parts of propylene glycol monomethyl ether, and then 20 partsof diethylaminopropylamine, and 114 parts of monomethylaminoethanol wereadded to the reaction mixture, and allowed to react at 120° C. for 4hours. The solution of base resin No. 4, which was an aminogroup-containing modified epoxy resin with a resin solids content of80%, was thus obtained. The base resin No. 4 had an amine value of 41 mgKOH/g, and a number average molecular weight of 2,700.

Table 1 shows the formulations and the characteristic values of baseresins Nos. 1 to 4 obtained in Production Examples 1 to 4.

TABLE 1 Production Production Production Production Example 1 Example 2Example 3 Example 4 Base resin No. 1 No. 2 No. 3 No. 4 Formulation (A1)(a1) Glyci-ale PP-300P (Note 1) 296 296 Denacol EX-821 (Note 2) 185Glyci-ale BPP-350 (Note 3) 340 (a2) jER828EL (Note 4) 1330 950 950 1330(a3) Bisphenol A 684 456 456 684 Catalyst Tetrabutylammonium bromide 1.00.8 0.8 1.0 Solvent Methyl isobutyl ketone 368 407 Propylene glycolmonomethyl 611 611 ether (A2) Mono methyl amino ethanol 137 113 114Diethyl amino propyl amine 20 Diethyl amine 110 Ketimine of 95 95diethylenetriamine with methyl isobutyl ketone Characteristic Aminevalue (mg KOH/g) 41 68 62 41 value Number average molecular weight 27002000 2200 2700 The numerals in the formulations are by parts. (Note 1)Glyci-ale PP-300P: trade name of an epoxy resin (diepoxy compound (a1))produced by Sanyo Chemical Industries, Ltd.; epoxy equivalent: 296;corresponding to compound (2) (R³ = CH₃, X = 1, Y = 7) (Note 2) DenacolEX-821: trade name of an epoxy resin (diepoxy compound (a1)) produced byNagase ChemteX Corporation; epoxy equivalent: 185; corresponding tocompound (2) (R³ = hydrogen atom, X = 1, Y = 4) (Note 3) Glyci-aleBPP-350: trade name of an epoxy resin (diepoxy compound (a1)) producedby Sanyo Chemical Industries, Ltd.; epoxy equivalent: 340; correspondingto compound (1) (R¹ = CH₃, R² = CH₃, m + n = 3) (Note 4) jER828EL: tradename of an epoxy resin (a2) produced by Japan Epoxy Resin; epoxyequivalent: 190; number average molecular weight: 380

Synthesis Example 1 Production of Xylene-Formaldehyde Resin

A 2-liter separable flask equipped with a thermometer, a refluxcondenser, and a stirrer was charged with 480 parts of 50% formalin, 110parts of phenol, 202 parts of 98% industrial sulfuric acid, and 424parts of m-xylene. The resulting mixture was allowed to react at 84° C.to 88° C. for 4 hours. After the reaction was completed, the reactionmixture was allowed to stand to separate a resin phase and a sulfuricacid aqueous phase. The resin phase was washed with water 3 times, andthen unreacted m-xylene was removed under the conditions of 20 to 30mmHg and 120° C. to 130° C. for 20 minutes. As a result, 480 parts of aphenol-modified xylene-formaldehyde resin having a viscosity of 1,050mPa·s (25° C.) were obtained.

Production Example 5 Production Example of Base Resin No. 5

A flask was charged with 1,140 parts of jER828EL (Note 4), 456 parts ofbisphenol A, and 0.2 parts of dimethylbenzylamine. The mixture wasallowed to react at 130° C. until the epoxy equivalent became 820.

Next, 420 parts of methylisobutylketone, and then 300 parts of thexylene-formaldehyde resin obtained in Synthesis Example 1 were added tothe reaction mixture. 95 parts of diethanol amine and 127 parts of aketimine of diethylenetriamine with methyl isobutyl ketone (purity: 84%,methyl isobutyl ketone solution) were then added to the resultingmixture and allowed to react at 120° C. for 4 hours. The solution ofbase resin No. 5, which was an amino group-containing modified epoxyresin with a resin solids content of 80%, was thus obtained. Base resinNo. 5 had an amine value of 47 mg KOH/g, and a number average molecularweight of 2,500.

Production of Blocked Polyisocyanate Curing Agent (B) Production Example6 Production Example of Curing Agent

270 parts of Cosmonate M-200 (trade name of crude MDI produced by MitsuiChemicals, Inc.) and 127 parts of methyl isobutyl ketone were added to areaction vessel and heated to 70° C. 236 parts of ethylene glycolmonobutyl ether were added dropwise over 1 hour, and the mixture washeated to 100° C. The mixture was sampled over time while thetemperature was maintained; when no absorption by unreacted isocyanategroups was observed by infrared absorption spectrometry, a curing agentwith a resin solids content of 80% was obtained.

Production Example 7 Production Example of Resin for Pigment Dispersion

1,010 parts of jER828EL (See Note 4) were blended with 390 parts ofbisphenol A, 240 parts of PLACCEL 212 (trade name ofpolycaprolactonediol produced by Daicel Chemical Industries; weightaverage molecular weight: about 1,250) and 0.2 parts ofdimethylbenzylamine, and the mixture was allowed to react at 130° C.until the epoxy equivalent became about 1,090.

Next, 134 parts of dimethylethanolamine and 150 parts of a 90% aqueouslactic acid solution were added to the reaction mixture, and thenallowed to react at 120° C. for 4 hours. Methyl isobutyl ketone wassubsequently added to the reaction mixture to adjust the solids content,thereby obtaining an ammonium salt-type resin for pigment dispersionhaving a solids content of 60%. The ammonium salt-type resin for pigmentdispersion had an ammonium salt concentration of 0.78 mmol/g.

Production Example 8 Production Example of Pigment Dispersion Paste

8.3 parts (solids content: 5 parts) of the resin for pigment dispersionhaving a solids content of 60% that were obtained in Production Example7, 14.5 parts of titanium oxide, 7.0 parts of refined clay, 0.3 parts ofcarbon black, 1 part of dioctyltin oxide, 1 part of bismuth hydroxide,and 20.3 parts of deionized water were added into a ball mill anddispersed for 20 hours. A pigment dispersion paste with a solids contentof 55% was thus obtained.

Production of Emulsion Production Example 9 Production Example ofEmulsion No. 1

81.3 parts (solids content: 65 parts) of base resin No. 1 obtained inProduction Example 1 were mixed with 37.5 parts (solids content: 30parts) of the curing agent obtained in Production Example 5 and 5 parts(solids content: 5 parts) of SUMILITERESIN PR-HF-3 (Note. 5). 15.0 partsof 10% acetic acid were further added to the resulting mixture anduniformly stirred. Thereafter, 155.2 parts of deionized water were addeddropwise over about 15 minutes with vigorous stirring to thereby obtainemulsion No. 1 with a solids content of 34%.

Production Examples 10 to 17 Production Examples of Emulsions Nos. 2 to9

Emulsions Nos. 2 to 9 were obtained in the same manner as in ProductionExample 9, except that the formulations shown in Table 2 were used.

TABLE 2 Pro. Pro. Pro. Pro. Pro. Pro. Pro. Pro. Exam. Pro. Exam. Exam. 9Exam. 10 Exam. 11 Exam. 12 Exam. 13 Exam. 14 Exam. 15 16 17 Emulsion No.1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 Component A Base resin81.3 81.3 81.3 68.8 87.5 No. 1 (65)   (65)   (65)   (55)   (70)  (solids content 80%) Base resin 81.3 No. 2 (65)   (solids content 80%)Base resin 81.3 No. 3 (65)   (solids content 80%) Base resin 81.3 No. 4(65)   (solids content 80%) Base resin 81.3 No. 5 (65)   (solids content80%) Component B Curing agent 37.5 37.5 37.5 37.5 37.5 37.5 37.5 37.537.5 (30)   (30)   (30)   (30)   (30)   (30)   (30)   (30)   (30)  Component C SUMILITERESIN  5.0  5.0  5.0  5.0  5.0 PR-HF-3 (Note 5) (5) (5)  (5)  (5)  (5)  SUMILITERESIN  5.0 TD-2131 (Note 6) (5)  Shonol  5.015.0 BRG-555 (Note 7) (5)  (15)   10% Acetic acid 15.0 15.0 15.0 15.015.0 15.0 15.0 15.0 15.0 Deionized water 155.2  155.2  155.2  155.2 155.2  155.2  157.7  155.2  154.0  Total (Solids content 34%) 294.0 294.0  294.0  294.0  294.0  294.0  294.0  294.0  294.0  (100)   (100)  (100)   (100)   (100)   (100)   (100)   (100)   (100)   Theparenthesized numerals in the formulations denote the solids content.(Note 5) SUMILITERESIN PR-HF-3: trade name of a phenol resin produced bySumitomo Bakelite Co., Ltd.; hydroxy value: 539 mg KOH/g. (Note 6)PHENOLITE TD-2131: trade name of a phenol resin produced by DICCorporation; hydroxy value: 539 mg KOH/g. (Note 7) Shonol BRG-555: tradename of a phenol resin produced by Showa Highpolymer Co., Ltd.; hydroxyvalue: 534 mg KOH/g.

Production of Cationic Electrodeposition Coating Composition Example 1

294 parts (solids content: 100 parts) of emulsion No. 1, 52.4 parts(solids content: 28.8 parts) of 55% pigment dispersion paste obtained inProduction Example 8, and 653.6 parts of deionized water were mixed toobtain 1,000 parts of a bath. Subsequently, 6.8 parts of 10% zirconiumhydrofluoric acid, and 10 parts of 10% nitric acid were added to thebath to obtain cationic electrodeposition coating composition No. 1.

Examples 2 to 28

Cationic electrodeposition coating compositions Nos. 2 to 28 wereproduced in the same manner as in Example 1, except that theformulations shown in Tables 3 to 5 were used.

TABLE 3 Exam. 1 Exam. 2 Exam. 3 Exam. 4 Exam. 5 Exam. 6 Exam. 7 Exam. 8Cationic electrodeposition No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No.8 coating composition EM Emulsion No. 1 294.0 294.0 (100)   (100)  Emulsion No. 2 294.0 (100)   Emulsion No. 3 294.0 (100)   Emulsion No. 4294.0 (100)   Emulsion No. 5 294.0 (100)   Emulsion No. 6 294.0 (100)  Emulsion No. 7 294.0 (100)   PP Pigment  52.4  52.4  52.4  52.4  52.4 52.4  52.4  52.4 dispersion  (28.8)  (28.8)  (28.8)  (28.8)  (28.8) (28.8)  (28.8)  (28.8) paste Deionized water 653.6 653.6 653.6 653.6653.6 653.6 653.6 653.6 Total (12.8% bath) 1000   1000   1000   1000  1000   1000   1000   1000   (128.8) (128.8) (128.8) (128.8) (128.8)(128.8) (128.8) (128.8) Component D 10% Zirconium  6.8  6.8  6.8  6.8 6.8  6.8  6.8 hydrofluoric   (0.68)   (0.68)   (0.68)   (0.68)   (0.68)  (0.68)   (0.68) acid H₂ZrF₆ 10% Titanium  10.3 hydrofluoric   (1.03)acid H₂TiF₆ Component E 10% Nitric  10.0  10.0  10.0  10.0  10.0  10.0 10.0  10.0 acid Relative to Mass of metal 300   300   300   300   300  300   300   300   the mass of of component the cationic D (ppm)electrodeposition Mass of 1000   1000   1000   1000   1000   1000  1000   1000   coating nitrogen composition oxide ion (ppm) Theparenthesized numerals in the formulations denote the solids content.

TABLE 4 (continuation of Table 3) Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex.14 Cationic electrodeposition coating composition No. 9 No. 10 No. 11No. 12 No. 13 No. 14 EM Emulsion No. 1 294.0 294.0 294.0 294.0 294.0294.0 (100)   (100)   (100)   (100)   (100)   (100)   PP Pigmentdispersion  52.4  52.4  52.4  52.4  52.4  52.4 paste  (28.8)  (28.8) (28.8)  (28.8)  (28.8)  (28.8) Deionized water 653.6 653.6 653.6 653.6653.6 653.6 Total (12.8% bath) 1000   1000   1000   1000   1000   1000  (128.8) (128.8) (128.8) (128.8) (128.8) (128.8) Component D 10%Zirconium hydrofluoric acid H₂ZrF₆ 10% Zirconyl nitrate ZrO(NO₃)₂  7.6  (0.76) 10% Zinc nitrate Zn(NO₃)₂  16.0  (1.6) 10% Yttrium nitrateY(NO₃)₃  9.3   (0.93) 10% Cupric nitrate Cu(NO₃)₂  8.8   (0.88) 10%Ytterbium nitrate Yb(NO₃)₃  6.2   (0.62) 10% Cerium nitrate Ce(NO₃)₃ 7.0  (0.7) 10% Indium nitrate In(NO₃)₃ 10% Bismuth nitrate Bi(NO₃)₃Component E 10% Nitric acid  5.9  4.3  3.7  4.2  6.8  6.0 Relative Massof metal of component D (ppm) 300   300   300   300   300   300   to theMass of nitrogen oxide ion (ppm) 1000   1000   1000   1000   1000  1000   mass of the cationic electrode position coating composition Ex.15 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Cationic electrodeposition coatingcomposition No. 15 No. 16 No. 17 No. 18 No. 19 No. 20 EM Emulsion No. 1294.0 294.0 294.0 294.0 294.0 294.0 (100)   (100)   (100)   (100)  (100)   (100)   PP Pigment dispersion  52.4  52.4  52.4  52.4  52.4 52.4 paste  (28.8)  (28.8)  (28.8)  (28.8)  (28.8)  (28.8) Deionizedwater 653.6 653.6 653.6 653.6 653.6 653.6 Total (12.8% bath) 1000  1000   1000   1000   1000   1000   (128.8) (128.8) (128.8) (128.8)(128.8) (128.8) Component D 10% Zirconium hydrofluoric acid  6.8  6.8 6.8  6.8 H₂ZrF₆   (0.68)   (0.68)   (0.68)   (0.68) 10% Zirconylnitrate ZrO(NO₃)₂ 10% Zinc nitrate Zn(NO₃)₂  16.0  (1.6) 10% Yttriumnitrate Y(NO₃)₃  9.3   (0.93) 10% Cupric nitrate Cu(NO₃)₂ 10% Ytterbiumnitrate Yb(NO₃)₃  6.2   (0.62) 10% Cerium nitrate Ce(NO₃)₃  7.0  (0.7)10% Indium nitrate In(NO₃)₃  11.0  (1.1) 10% Bismuth nitrate Bi(NO₃)₃ 5.7   (0.57) Component E 10% Nitric acid  5.1  7.3  4.3  3.7  6.8  6.0Relative Mass of metal of component D (ppm) 300   300   600   600  600   600   to the Mass of nitrogen oxide ion (ppm) 1000   1000   1000  1000   1000   1000   mass of the cationic electrode position coatingcomposition The parenthesized numerals denote the solids content.

TABLE 5 (continuation of Table 3) Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex.26 Ex. 27 Ex. 28 Cationic electrodeposition No. 21 No. 22 No. 23 No. 24No. 25 No. 26 No. 27 No. 28 coating composition EM Emulsion No. 1  294.0   294.0   294.0   294.0   294.0   294.0   294.0   294.0 (100)(100) (100) (100) (100) (100) (100) (100) PP Pigment   52.4   52.4  52.4   52.4   52.4   52.4   52.4   52.4 dispersion   (28.8)   (28.8)  (28.8)   (28.8)   (28.8)   (28.8)   (28.8)   (28.8) paste Deionizedwater   653.6   653.6   653.6   653.6   653.6   653.6   653.6   653.6Total (12.8% bath) 1000  1000  1000  1000  1000  1000  1000  1000   (128.8)   (128.8)   (128.8)   (128.8)   (128.8)   (128.8)   (128.8)  (128.8) Component D 10% Zirconium    6.8    6.8    6.8    6.8hydrofluoric    (0.68)    (0.68)    (0.68)    (0.68) acid H₂ZrF₆ 10%Titanium   10.3 hydrofluoric    (1.03) acid H₂TiF₆ 10% Cobalt    9.3nitrate    (0.93) Co(No₃)₂ 10%    7.0    7.0 Praseodymium    (0.7)   (0.7) nitrate Pr(No₃)₃ 10% Zinc    8.4 acetate    (0.84) Zn(CH₃COO)₂10% Cerium    6.8    6.8 acetate    (0.68)    (0.68) Ce(CH₃COO)₃ 10%   8.8 Neodymium    (0.88) acetate Nd(CH₃COO)₃ Component E 10% Nitric   3.7    6.0   0.0   10.0   10.0    6.0   10.0   10.0 acid Relative toMass of metal 300 300 300 300 600 600 600 600 the mass of of componentthe cationic D (ppm) electrodeposition Mass of 1000  1000  1000  1000 1000  1000  1000  1000  coating nitrogen composition oxide ion (ppm) Theparenthesized numerals in the formulations denote the solids content.

Comparative Examples 1 to 6

Cationic electrodeposition coating compositions Nos. 29 to 34 wereproduced in the same manner as in Example 1, except that theformulations shown in Table 6 were used.

TABLE 6 Comp. Comp. Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex.5 Ex. 6 Cationic electrodeposition No. 29 No. 30 No. 31 No. 32 No. 33No. 34 coating composition EM Emulsion No. 1 294.0 294.0 294.0 294.0(100)   (100)   (100)   (100)   Emulsion No. 8 294.0 (100)   EmulsionNo. 9 294.0 (100)   PP Pigment  52.4  52.4  52.4  52.4  52.4  52.4dispersion  (28.8)  (28.8)  (28.8)  (28.8)  (28.8)  (28.8) pasteDeionized water 653.6 653.6 653.6 653.6 653.6 653.6 12.8% Bath 1000  1000   1000   1000   1000   1000   (128.8) (128.8) (128.8) (128.8)(128.8) (128.8) Component D 10% Zirconium  6.8  6.8  6.8  14.0hydrofluoric   (0.68)   (0.68)   (0.68)  (1.4) acid H₂ZrF₆ 10% Titanium 10.3 hydrofluoric   (1.03) acid H₂TiF₆ Component E 10% Nitric  10.0 10.0 —  10.0 — — acid Relative to Mass of metal 300   300   300   —300   600   the mass of of component D the cationic (ppm)electrodeposition Mass of 1000   1000   — 1000   — — coating nitrogenoxide composition ion The parenthesized numerals in the formulationsdenote the solids content.

Substrate to be Coated

Cold rolled steel sheets (70 mm×150 mm×0.8 mm) that had not beensubjected to chemical conversion treatment were immersed in anultrasonic cleaner containing toluene, and subjected to ultrasonicdegreasing for 30 minutes, thereby obtaining “substrates to be coated”.

Preparation and Evaluation of Test Sheets Containing CationicElectrodeposition Coating Films

The temperature of each bath of cationic electrodeposition coatingcompositions Nos. 1 to 34 was adjusted to 40° C., and a “substrate to becoated” was immersed in a bath for 120 seconds (Step 1).Electrodeposition coating (Step 2) was then performed at 200V, for 180seconds, and baking was conducted at 170° C. for 20 minutes, therebyobtaining a test sheet having a thickness of 15 μm (when dried). Eachtest sheet was evaluated according to the following conditions. Tables 7to 9 show the results of the Examples, and Table 10 shows the results ofthe Comparative Examples.

TABLE 7 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Example 7 Example 8 Cationic No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7No. 8 electrodeposition coating composition Finish (coating B B B B B BB B film condition) (Note 8) Hot salt water B B B B B B A B immersionresistance (Note 9) Exposure B B B B B B A B resistance (Note 10)Coating B B B B B B B B composition stability (Note 11) Comprehensive BB B B B B A B evaluation (Note 12)

TABLE 8 (continuation of Table 7) Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex.14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Cationic No. 9 No. 10 No.11 No. 12 No. 13 No. 14 No. 15 No. 16 No. 17 No. 18 No. 19 No. 20electrodeposition coating composition Finish (coating B B B B B B B B BB B B film condition) (Note 8) Hot salt water B B B B B B B B A A A Aimmersion resistance (Note 9) Exposure B B B B B B B B A A A Aresistance (Note 10) Coating B B B B B B B B B B B B compositionstability (Note 11) Comprehensive B B B B B B B B A A A A evaluation(Note 12)

TABLE 9 (continuation of Table 7) Example Example Example ExampleExample Example Example Example 21 22 23 24 25 26 27 28 Cationic No. 21No. 22 No. 23 No. 24 No. 25 No. 26 No. 27 No. 28 electrodepositioncoating composition Finish (coating B B B B B B B B film condition)(Note 8) Hot salt water B B B B B A A A immersion resistance (Note 9)Exposure B B B B B A A A resistance (Note 10) Coating B B B B B B B Bcomposition stability (Note 11) Comprehensive B B B B B A A A evaluation(Note 12)

TABLE 10 Comp. Comp. Comp. Comp. Comp. Comp. Exam. 1 Exam. 2 Exam. 3Exam. 4 Exam. 5 Exam. 6 Cationic No. 29 No. 30 No. 31 No. 32 No. 33 No.34 electro- deposition coating composition Finish (coating B B — — — —film condition) (Note 8) Hot salt water D C C D C C immersion resistance(Note 9) Exposure D D C D C C resistance (Note 10) Coating D B B B B Bcomposition stability (Note 11) Comprehensive D D D D D D evaluation(Note 12) (Note 8) Finish (condition of coating film): Each test sheetwas cut, and the conditions of the coating films (lower layer and upperlayer) were observed using HF-2000 (a field emission transmissionelectron microscope produced by Hitachi Ltd.) The conditions of thecoating films were evaluated according to the following criteria. B: Theboundary between the coating films (lower layer and upper layer) wasunclear, but slight layer separation was observed. —: No layerseparation was observed. (Note 9) Hot salt water immersion resistance:Each test sheet was immersed in 5 wt. % of salt water at 50° C. for 480hours, and a Sellotape (trade name) peeling test was performed. Thepercentage (%) of the portion that peeled off was measured. A: Thepercentage of peeled portion relative to the whole coating film was lessthan 5%. B: The percentage of peeled portion relative to the wholecoating film was not less than 5% and less than 10%. C: The percentageof peeled portion relative to the whole coating film was not less than10% and less than 20%. D: The percentage of peeled portion relative tothe whole coating film was not less than 20%. (Note 10) ExposureResistance Test WP-300 (trade name of an aqueous intermediate coatingcomposition produced by Kansai Paint Co., Ltd.) was sprayed over a testsheet obtained in the same manner as above to a cured film thickness of25 μm, and then baked at 140° C. for 30 minutes using an electric hotair dryer. Thereafter, NEO AMILAC 6000 (trade name of a topcoatcomposition produced by Kansai Paint Co., Ltd.) was sprayed over theintermediate coating film to a cured film thickness of 35 μm. Baking wasthen conducted using an electric hot air dryer at 140° C. for 30minutes, thereby obtaining an exposure test sheet. The coating film onthe resulting exposure test sheet was cross-cut with a knife so that thecut reached the substrate. The sheet was placed flatly and exposed tooutside weather conditions in Chikura-machi, Chiba Prefecture (beachside), for one year. The exposure resistance was then evaluated, basedon the width of rust or blister from the cut portion. A: The maximumwidth of rust or blister from the cut was less than 2.0 mm (on oneside). B: The maximum width of rust or blister from the cut was not lessthan 2.0 mm and less than 3.0 mm (on one side). C: The maximum width ofrust or blister from the cut was not less than 3.0 mm and less than 4.0mm (on one side). D: The maximum width of rust or blister from the cutwas not less than 4.0 mm (on one side). (Note 11) Coating compositionstability: Each of the film forming agents was sealed in a vessel at 30°C. for 30 minutes and then stirred. The total amount of film formingagent was filtered through a 400-mesh sieve. The amount of residue(mg/L) was measureded. B: less than 10 mg/L C: Not less than 10 mg/L,and less than 15 mg/L D: Not less than 15 mg/L (Note 12) Comprehensiveevaluation: In the field of cationic electrodeposition coatingcompositions to which the present invention belongs, it is desirablethat the cationic electrodeposition coating composition excel in termsof finish, hot salt water immersion resistance, exposure resistance, andcoating composition stability. It is most desirable that the cationicelectrodeposition coating composition receive the highest rating for allof the four properties (A is the highest rating for hot salt waterimmersion resistance, and exposure resistance; and B is the highestrating for finish and coating composition stability). Specifically, acomprehensive evaluation was conducted according to the followingcriteria: A: hot salt water immersion resistance and exposure resistancewere rated as A, and finish and coating composition stability were ratedas B. B: Four properties were rated as A or B, including not more thanone A. C: Four properties were rated as A, B, or C, including at leastone C. D: Of the four properties, at least one property was rated as Dor “—”.

INDUSTRIAL APPLICABILITY

The present invention can provide a coated article that exhibitsexcellent anti-corrosion properties even on an untreated steel sheet.

1. A cationic electrodeposition coating composition comprising aminogroup-containing modified epoxy resin (A), blocked polyisocyanate curingagent (B), phenol resin (C), metal compound (D), and nitrogen oxide ion(E); the cationic electrodeposition coating composition comprising themetal compound (D) in an amount of 10 to 10,000 ppm calculated as metal(on a metal mass basis) and the nitrogen oxide ion (E) in an amount of50 to 10,000 ppm, relative to the mass of the cationic electrodepositioncoating composition, the amino group-containing modified epoxy resin (A)being a resin obtainable by reacting modified epoxy resin (A1) having anepoxy equivalent of 500 to 2,500 and amine compound (A2), the modifiedepoxy resin (A1) being obtainable by reacting diepoxy compound (a1),epoxy resin (a2) having an epoxy equivalent of 170 to 500, and bisphenolcompound (a3), the diepoxy compound (a1) being compound (1) representedby Formula (1) below,

wherein R¹ is the same or different, and each represents a hydrogen atomor a C₁₋₆ alkyl group; R² is the same or different, and each representsa hydroxy atom or C₁₋₂ alkyl group, and m and n, which represent thenumber of repeating units of the portion having an alkylene oxidestructure, are integers where m+n=1 to 20, and/or compound (2)represented by Formula (2) below,

wherein R³ represents a hydrogen atom or C₁₋₆ alkyl group, X is aninteger of 1 to 9, and Y is an integer of 1 to 50; when Y is 2 or more,each R³ in the repeating unit is the same or different, and the metalcompound (D) being a compound of at least one metal (d) selected fromthe group consisting of zirconium, titanium, cobalt, vanadium, tungsten,molybdenum, copper, indium, zinc, aluminum, bismuth, yttrium,lanthanoids, alkali metals, and alkaline earth metals.
 2. The cationicelectrodeposition coating composition according to claim 1, wherein theamino group-containing modified epoxy resin (A) is contained in anamount of 30 to 75 parts by mass, the blocked polyisocyanate curingagent (B) is contained in an amount of 10 to 40 parts by mass, and thephenol resin (C) is contained in an amount of 3 to 35 parts by mass,based on the total solids mass (100 parts by mass) of the aminogroup-containing modified epoxy resin (A), blocked polyisocyanate curingagent (B), and phenol resin (C).
 3. The cationic electrodepositioncoating composition according to claim 1, wherein the modified epoxyresin (A1) is obtainable by reacting 1 to 35 mass % of the diepoxycompound (a1), 10 to 80 mass % of the epoxy resin (a2), and 10 to 60mass % of the bisphenol compound (a3), based on the total solids mass ofthe diepoxy compound (a1), epoxy resin (a2), and bisphenol compound(a3).
 4. The cationic electrodeposition coating composition according toclaim 1, wherein R¹ in the Formula (1) or R³ in the Formula (2) is amethyl group or hydrogen atom.
 5. The cationic electrodeposition coatingcomposition according to claim 1, wherein the metal compound (D)consists of a zirconium compound, or comprises at least one compoundselected from the group consisting of zirconium compounds and titaniumcompounds, and a compound of at least one metal selected from the groupconsisting of cobalt, vanadium, tungsten, molybdenum, copper, indium,zinc, aluminum, bismuth, yttrium, lanthanoids, alkali metals, andalkaline earth metals.
 6. The cationic electrodeposition coatingcomposition according to claim 1, wherein the solids content of thecationic electrodeposition coating composition is 5 to 40 mass %.
 7. Acoated article obtainable by immersing a metal substrate in anelectrodeposition coating composition bath containing the cationicelectrodeposition coating composition according to claim 1, andperforming electrodeposition coating.
 8. The cationic electrodepositioncoating composition according to claim 2, wherein the modified epoxyresin (A1) is obtainable by reacting 1 to 35 mass % of the diepoxycompound (a1), 10 to 80 mass % of the epoxy resin (a2), and 10 to 60mass % of the bisphenol compound (a3), based on the total solids mass ofthe diepoxy compound (a1), epoxy resin (a2), and bisphenol compound(a3).
 9. A coated article obtainable by immersing a metal substrate inan electrodeposition coating composition bath containing the cationicelectrodeposition coating composition according to claim 2, andperforming electrodeposition coating.
 10. A coated article obtainable byimmersing a metal substrate in an electrodeposition coating compositionbath containing the cationic electrodeposition coating compositionaccording to claim 3, and performing electrodeposition coating.
 11. Acoated article obtainable by immersing a metal substrate in anelectrodeposition coating composition bath containing the cationicelectrodeposition coating composition according to claim 4, andperforming electrodeposition coating.
 12. A coated article obtainable byimmersing a metal substrate in an electrodeposition coating compositionbath containing the cationic electrodeposition coating compositionaccording to claim 5, and performing electrodeposition coating.
 13. Acoated article obtainable by immersing a metal substrate in anelectrodeposition coating composition bath containing the cationicelectrodeposition coating composition according to claim 6, andperforming electrodeposition coating.
 14. A coated article obtainable byimmersing a metal substrate in an electrodeposition coating compositionbath containing the cationic electrodeposition coating compositionaccording to claim 8, and performing electrodeposition coating.